


I Wish You WOuld Write... 3

by equilateral_asshat



Series: I wish you would write... [3]
Category: Gravity Falls
Genre: F/M, Marco Polo gets crazy sometimes, Underage Drinking, pinecest - Freeform, pinescest - Freeform
Language: English
Status: Completed
Published: 2018-12-16
Updated: 2018-12-16
Packaged: 2019-09-20 07:07:22
Rating: Mature
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,457
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/17018055
Author URL: https://archiveofourown.org/users/equilateral_asshat/pseuds/equilateral_asshat
Summary: The "I wish you would write" stories are small fics written from prompts sent by users who finish the statement with the type of fic they'd like to see.





	I Wish You WOuld Write... 3

**Author's Note:**

> I wish you would write a fic where.... Teen mabes and dip are buzzed and the last two people at a pool party at night. (aka pool sex or slight grinding and more making out)
> 
> [Sorry for taking so long, life and other projects got in the way! Gonna say they’re just at the edge of 17-18 here.]

Dipper’s head was swimming dizzily.

Well, so was he, technically, being in the swimming pool and all. But the couple of drinks he’d been talked into having earlier in the night gave him enough of a buzz that his head, though above water, seemed to be floating along in a haze. The entire night was a bit of a blur now.

Earlier, Wendy had given the Pines twins an unofficial invite to a party at Thomson’s, and they had eagerly accepted. Upon arrival they found the party swarming with teenagers, college students, and booze everywhere. Dipper had questioned the flagrant disregard for the law, but Wendy pointed out that Blubs and Durland were, in their usual manner, unlikely to intervene. After conceding to that point, a red plastic cup with a bubbly fluid inside had been shoved into his hands. A few drinks and several hours later, he and his sister were the only ones still conscious, and they were playing a drunken game in the pool.

“ _Maaarrrcooo,_ ” he heard Mabel slur out, giggling as she turned this way and that in the water. She was wearing a red two piece, which was covered with sequins that his sister had sewn to it on her own. Years ago the suit had been plenty concealing, but as they had grown, so had certain… assets of his sister’s, and while it still fit, certain things were no longer being left to the imagination.

“ _Pooolooo,_ ” he mumbled back, trying to glide past her as quietly as possible. She twisted towards the sound of his voice and lunged, splashing back down into empty water as he kicked away in an inebriated struggle to avoid capture. She surfaced, shaking wet hair from her face and sputtering. After grabbing at the water a few more times, she huffed in defeat.

“ _Marco…_ ” Her voice had a much more determined tone this time, but Dipper’s earlier narrow escape had bolstered him with drunken confidence. As he tried to float past quietly, he half-whispered in response.

“ _Polo_ ,” came his quiet reply, but with an unseen aptitude, Mabel’s hand shot out like a striking cobra, grabbing at her twin brother. Her successful capture caused him to flail in the water.

“AHA!” she declared, cracking an eye open and-oh, ooohhh boy. In her rush to win this round she had gotten a hold of her brother alright. Right there, between the legs, on the front of his swim trunks. Hooboy, this was awkward, even for drunk Mabel! So… why hadn’t she let go yet? With a concentrated effort, she pried her fingers away from her sibling’s crotch. Then, a second later, her eyes.

“Mabel, th-that, that’s cheating, somehow! I call redo, y’can’t count it when you grab somebody THERE,” Dipper mumbled, quickly shoving his hands under the water to cover himself through his shorts.

“I dun ‘member that in the rules, bro-bro,” she giggled, giving him a playful shove. “B’sides, not like you have anythin’ to be ‘shamed of, unless swim trunks add more than they oughta.” She could see him, even in the dim light of the security bulb over the pool, turning red. “’m sorry, Dip. It was an accident, y’know I wouldn’t aim for that, r-right?”

“F-fine, let’s just play,” he retorted, closing his eyes and taking a deep breath or two to steady his drunken nerves. She grinned wider and backed away a couple of feet. “ _Marco…_ ”

“ _Polooo,”_ she called back in a sing-song tone. Her brother’s head snapped in her direction immediately, and he edged towards the sound sideways, hands up, shoulder-width apart as he stalked.

“ _Marco?_ ” Mabel circled back around, getting behind her brother as quietly as she could, before attempting to spook him out of his skin.

“ _Polo!_ ” she half-shouted. Dipper jumped, as she’d anticipated, but he also twisted and his hands snatched out, finding paydirt.

“Gotcha!” He cracked his eyes open, grinning victoriously at his sister. But her gaze was down on his hands. He flexed his fingers, and found that the flesh he grasped was ample, soft and beneath a thin layer of sequins and fabric. He could feel his face flushing to match the bikini top Mabel was in, that, at the moment, was also firmly held in his hands. His smile quickly gave way to a look of panic.

“Y’sure did, damn broseph,” she replied, giving her chest a push forward against his grasp. Before he could yank his hands back and start apologizing, she placed a hand on either of his wrists, giving a reaffirming squeeze. “D’ya think this makes us even?”

“I… uh…” Even through the layer of poolwater on his skin, she could see sweat beading on his forehead. She inched closer in the water, his arms bending at the elbow while his hands made no effort to release themselves from either her grasp or her bosom.

“‘s that a yes or a no?” Maybe it was the alcohol, maybe it was the look of bewilderment and curiosity on his face. Maybe it was the way his hands kept flexing, kneading gently at her breasts. Or the moment of excitement when she had groped him earlier. It could have even been the way he nibbled at his lower lip while his brain tried to drunkenly process this information. Whatever it was, Mabel found herself wanting to see how far this new “game” could go.

She kissed him.

Dipper’s hands opened as soon as her lips found his, trying to pull back away in a moment of panic and confusion, but then his fingers were soon again groping at the handfuls of breast his sister was practically offering. His drunken inner voice of reason told him that this was wrong, they were drunk, he couldn’t do this. Then she kissed him again, more insistently, and his inner voice found itself struggling to be heard. He broke the kiss.

“M-Mabes, we, we can’t d’this! ‘s not right,” he mumbled against the assault of her lips on his. She gently plucked at his lower lip with her teeth.

“Why nooot?” she whimpered. Her legs both lifted up and wrapped themselves around his waist, and her arms mirrored the action around his neck. She ground her hips to his, and found that the cool water of the pool was doing nothing to counteract the rush of blood her brother was experiencing below the belt. “Cuz we’re r’lated?”

“Y-you’re drunk,” he muttered into the next kiss, pushing back against her lips with his own. Were her lips always so soft? Did she always taste this sweet? “W-we’re both drunk.”

“’s that all?” Her voice was a soft whisper against his jawline. Her crotch started to grind into his own. His legs wobbled under the water as a half-hearted moan gurgled up out of his throat, and he shook his head.

“N-no?” She planted another kiss on his lips. “I mean, yes?” Another kiss, and this time her tongue slithered out along his lips. He growled a bit, and she licked again as his lips parted, both tongues starting a small shoving match. She broke the kiss after a second or two.

“So us bein’ sibs isn’t-” she started to inquire, but Dipper pressing his lips feverishly to hers stopped her from pushing that side of the issue. She hummed into the embrace of their lips. Her brother broke the kiss with a panting, desperate breath.

“We shouldn’t…” he huffed sadly. She pouted and ground her hips to his again, which elicited a sharp gasp, sucked through clenched teeth. “Mabel..”

The name was whispered against her lips like a prayer and curse combined. She nibbled at his lower lip, eager to hear her name like that again, when an exasperated shout came from the backdoor of the house. It was Wendy.

“M-Mabel, Dipper! We all gotta bounce, Thomson’s folks are comin’ home early and-whoa.” The twins separated in a blink, both turning deep red. How much had she seen? “You two still swimmin’? You’ve been in there for hours, you’ll be wrinklier than Stan soon.” She grabbed a pair of towels and chucked them at the twins as they came to the edge of the pool.

They both wrapped themselves up and grabbed their respective clothing where it had been tossed before they started swimming. Then, along with a bunch of other kids being roused by Wendy, dispersed in one of several directions people were taking in an effort to escape.

A couple of blocks away, Mabel leaned over and planted a kiss on her brother’s cheek. He flushed crimson in the light of a streetlamp. “What’s that for?”

“Wanna play _Marco-Polo_ in the attic?” she asked. Dipper turned with a raised eyebrow, then as realization set in, merely nodded.


End file.
